NCLEX Study Guide: Cranial Nerves Made Easy (Mnemonics & Assessment)

Cranial nerves are a set of twelve pairs of nerves that emerge directly from the brain. They primarily innervate structures of the head and neck, playing essential roles in sensory perception, motor control, and autonomic functions in the head and neck region.

Mastering these nerves is critical for the NCLEX. This guide provides the best memory tricks and a complete breakdown of how to assess each nerve’s function.

1. Cranial Nerve Mnemonics (Names and Functions)

Memorizing the order and function (Sensory, Motor, or Both) of the 12 cranial nerves is simple when you use these classic nursing mnemonics.

Mnemonic for Nerve Names (CN I to CN XII):

On Occasion Our Trusty Truck Acts Funny, Very Good Vehicle Any How.
Alternative: Only One Of The Two Athletes Felt Very Good, Victorious, And Healthy.

Mnemonic for Nerve Function (Sensory, Motor, or Both):

Some Say Marry Money But My Brother Says Big Brains Matter Most.

2. Cranial Nerves I, II, and III

CN I: Olfactory Nerve (Sensory)

Function: The Olfactory nerve is responsible for smell (olfaction), transmitting sensory information from the nose to the brain.
Assessment Test: Patients are asked to identify various scents. Have the patient identify the smell of a substance with their eyes closed.

CN II: Optic Nerve (Sensory)

Function: The Optic nerve is responsible for vision, transmitting visual information from the eyes to the brain.
Assessment Test: Visual acuity, visual fields, pupillary reflexes, and fundoscopic examination are used to assess optic nerve function. A Snellen chart is often used standing 20 feet away, covering one eye at a time.

CN III: Oculomotor Nerve (Motor)

Function: Controls most eye movements, including upward, downward, and medial movements, as well as pupil constriction and eyelid opening.
Assessment Test: Assess for upward, downward, and medial eye movements, as well as pupillary reflexes and eyelid opening. Use a penlight to check light reaction and finger to check accommodation.

3. Cranial Nerves IV, V, and VI

CN IV: Trochlear Nerve (Motor)

Function: Controls downward and inward eye movements.
Assessment Test: Assess for downward and inward eye movements. Use a penlight and move it medially and downwards.

CN V: Trigeminal Nerve (Both)

Function: Responsible for sensation in the face (including touch, pain, and temperature), as well as controlling the muscles involved in chewing (mastication).
Assessment Test: Assess facial sensation by touching various areas of the face with a cotton swab or sharp object. Test motor function by asking the patient to clench their jaw or move it from side to side.

CN VI: Abducens Nerve (Motor)

Function: Controls lateral eye movement, allowing the eye to move outward.
Assessment Test: Assess lateral eye movement by observing the patient’s ability to move their eyes outward. Use a penlight and move it sideways.
Note: CN III, CN IV, and CN VI are often tested together.

4. Cranial Nerves VII and VIII

CN VII: Facial Nerve (Both)

Function: Controls facial expression muscles, taste sensation for the anterior two-thirds of the tongue, and provides secretomotor innervation to various glands, including the salivary and lacrimal glands.
Assessment Test: Assess facial symmetry at rest and with various facial expressions. Ask the patient to smile, raise eyebrows, close eyes, and puff out cheeks. Test taste sensation (sweet & salty) on the anterior tongue, and check for normal tear and saliva production.

CN VIII: Vestibulocochlear Nerve (Sensory)

Function: Responsible for transmitting auditory information (hearing) from the cochlea and vestibular information (balance and spatial orientation) from the inner ear to the brainstem.
Assessment Test: Assess hearing acuity using tuning forks or audiometry tests. You can also test hearing by whispering near the patient’s ear. Evaluate balance and vestibular function through various positional maneuvers and balance tests, such as asking the patient to walk across the room and back.

5. Cranial Nerves IX and X

CN IX: Glossopharyngeal Nerve (Both)

Function: Responsible for sensation in the posterior third of the tongue, taste sensation for the posterior one-third of the tongue, monitoring blood pressure and blood gas levels, and innervating muscles involved in swallowing (pharynx).
Assessment Test: Assess taste sensation on the posterior one-third of the tongue, evaluate the gag reflex, and monitor blood pressure and heart rate responses to stimuli. Motor function can be evaluated by having the patient say “ahhhh” to check if the uvula rises symmetrically.

CN X: Vagus Nerve (Both)

Function: Responsible for a wide range of autonomic functions, including regulating heart rate, controlling gastrointestinal peristalsis, controlling sweating, and regulating various organs such as the liver, spleen, and pancreas. It also plays a role in vocal cord movement and swallowing.
Assessment Test: Assess swallowing function, evaluate vocal cord movement, and monitor heart rate and gastrointestinal function.
Note: CN IX & CN X work together for the gag reflex and swallowing.

6. Cranial Nerves XI and XII

CN XI: Accessory Nerve (Motor)

Function: Controls movements of the sternocleidomastoid and trapezius muscles, which are involved in head and shoulder movements.
Assessment Test: Assess strength and symmetry of shoulder shrugging and head rotation against resistance.

CN XII: Hypoglossal Nerve (Motor)

Assessment Test: Assess tongue strength and mobility by asking the patient to protrude their tongue, move it from side to side, and press it against the cheek.

Function: Controls movements of the tongue muscles, facilitating functions such as swallowing, speech articulation, and tongue movement for tasks like chewing and licking.

Interactive Practice NCLEX Questions

4. The nurse has administered prescribed IV mannitol (Osmitrol) to an unconscious patient.
Which parameter would the nurse monitor to determine the medication‘seffectiveness?
a. Blood pressure
b. Oxygen saturation
c. Intracranial pressure
d. Hemoglobin and hematocrit

Click to View Answer & Rationale

ANS: C
Mannitol is an osmotic diuretic and will reduce cerebral edema and intracranial pressure. It
may initially reduce hematocrit and increase blood pressure, but these are not parameters for
evaluation of the effectiveness of the drug. O2 saturation will not directly improve because
of mannitol administration.

5. A patient with a head injury o al stimulation, curses when stimulated, and does not
respond to a verbal commandptoenmsohviseebyuetsattotevmeprbts to push away a painful stimulus.
How would the nurse record the patient‘s Glasgow Coma Scale score?
a. 9
b. 11
c. 13
d. 15

Click to View Answer & Rationale

ANS: B
The patient has scores of 3 for eye opening, 3 for best verbal response, and 5 for best motor
response.

10. A patient who has a suspected epidural hematoma is admitted to the emergency department.
Which action will the nurse expect to take?
a. Administer IV furosemide (Lasix).
b. Prepare the patient for craniotomy.
c. Initiate high-dose barbiturate therapy.
d. Type and crossmatch for blood transfusion.

Click to View Answer & Rationale.

ANS: B
The principal treatment for epidural hematoma is rapid surgery to remove the hematoma and
prevent herniation. If intracranial pressure is elevated after surgery, furosemide or high-dose
barbiturate therapy may be needed, but these will not be of benefit unless the hematoma is
removed. Minimal blood loss occurs with head injuries, and transfusion is usually not
necessary.